1. Field of the Invention
This invention relates to an electroconductive ceramic having good electroconductivity and a process for the production of the ceramic.
2. Description of the Prior Art
The materials such as silicon carbide (SiC), lanthanum chromate (LaCrO.sub.3) and zirconia (ZrO.sub.2) are known as electroconductive ceramic materials. These electroconductive ceramic materials, however, have a relatively high electrical resistance which does not become lower than about 10.sup.-2 .OMEGA.cm even when heated at a temperature as high as 1,000.degree. C. Also, these ceramic materials have a negative resistance-temperature characteristics, that is, their electrical resistance decreases as the temperature increases, so that when heated at a high temperature, they tend to cause a thermorunaway due to sharp increase of electric current, making the temperature control very difficult. Further, said ceramic materials are usually porous and hence low in mechanical strength.
Furthermore, an electroconductive ceramic comprising ZrB.sub.2, TiB.sub.2, TiN, ZrN, TaC, ZnC or etc. and a matrix of SiC is known. This is disclosed in Y. Matsushita et al U.S. Ser. No. 497,577 filed May 24, 1983 (corresponding to Japanese Patent Application No. 89926/82.)